TM 5-6675-323-14
NOTE
F a c t o r y d e t e r m i n e d RT v a l u e i s g i v e n o n C a l i b r a t i o n R e c o r d S h e e t
provided with equipment. Alinement is performed as a check.
(7) Place planimeter near shape to remeasured so that length of tracer arm
lies along imaginary line through center of shape.
S e t wheels so that axles form 90
degree angle with tracer arm.
(8) Make practice trace to be sure tracer arm will cover area in one
operation.
(9) Determine area constant, C (multiplier), using the following formula:
) 2 x
AT
(S
C
C
=
RT
Area of constant
C
=
Area of test rule (given on Calibration Record Sheet
=
A
T
p r o v i d e d with equipment)
Encoder count for each revolution (given on Calibration Record
=
R
S h e e t provided with equipment)
T
Scale ratio
S
=
c
Sc b y u s i n g t h e f o l l o w i n g f o r m u l a :
(a)
Determine
=
CL x
RL
S
c
=
Scale
ratio
Sc
= Length constant (paragraph 9-6.2ad)
CL
= Counts per inch (given on Calibration Record
RL
S h e e t provided with equipment)
Example:
(b)
C L value (0.018447) obtained from linear measurements on aerial
photographs (paragraph 9-6.2ad).
= 0.018447 X 724 = 13.355628
Sc
= 178.372799
( SC ) 2
U s e v a l u e s p r o v i d e d o n C a l i b r a t i o n R e c o r d S h e e t f o r AT a n d RT .
(c)
F o r this example, the value for R T i s 2 1 5 7 a n d A T i s 1 2 . 5 4 .
T h e formula can now be computed on the calculator.
178.372799 X 12.54
2236.794903
=
C=
2157
2157
= 1.036993
9-86
